Technical Notes

In this technical note we explore Transient absorption (flash photolysis), which is a powerful tool to understand many photochemical properties and reactions, from measuring the energy levels and lifetimes of excited singlet and triplet states, to measuring electron and energy transfer rates of paired molecular systems, and even photocatalysis intermediates and products.

In this technical note we describe the operation of Batch Mode and demonstrate two examples where it is useful: temperature maps of anisotropy and measurements on multiple samples.

This technical note will introduce some basic theory about polarisation of light and polarised Raman spectroscopy, before demonstrating different types of samples the RM5 can analyse using this technique.

Excitation-emission spectroscopy becomes increasingly useful in the study of photo-luminescent materials. The spectral selectivity of the technique enables the quantification of multiple emitting sites in rare-earth doped crystals, as well as the rapid acquisition of polycyclic aromatic hydrocarbons (PAH) in contaminated water.

In flash photolysis, a short pulse of light generates a transient (temporary) species in a sample; e.g. a radical intermediate or a short-lived excited state. As the sample relaxes back to the ground state or the final reaction products, the changes occurring are recorded as a function of time using a spectroscopic technique. A flash photolysis spectrometer typically monitors the change in absorption as a function of time, utilising a second light source (probe) besides the excitation (pump) pulse going through the sample. This technique is also known as transient absorption (TA). This technical note is aimed as an introduction to nanosecond flash photolysis for newcomers to the technique. We describe the operation of the LP980 spectrometer and show examples of measurements, with references to real-life applications.

Luminescent materials used in lighting are standardized by the International Commission on Illumination (CIE). This standardisation is important for the lighting industry and is based on the illuminating conditions, the brightness and the observer. In this technical note, a series of phosphors emitting across the visible range were characterised in an FS5 Spectrofluorometer and their chromaticity coordinates calculated in its integrated software package, Fluoracle®.

Reliable fluorescence standards and stable fluorescent probes for bio-analytics and chemistry are as important as sensitive indicator fluorophores that utilise the outstanding property of fluorescence of being highly sensitive to the fluorophore’s micro-environment. In this technical note we use the FS5 Spectrofluorometer to show the quenching of fluorescence with temperature. By using the extended capabilities of FS5-TCSPC we also record, for the same set of temperatures, the fluorescence lifetimes. We can show that temperature dependence of Rhodamine B is exclusively caused by dynamic quenching.

The absorbance or optical density of a substance is inherent in all aspects of spectroscopy and follows the Beer-Lambert law. In this Technical Note, our FS5 Spectrofluorometer is equipped with a silicon detector that allows for transmission and absorbance measurements. After the transmission scans of the sample and reference are complete, they can be joined to calculate the absorbance through the absorption wizard in our operating software, Fluoracle.

Detection of Singlet Oxygen is of particular interest in a multitude of applications such as photodynamic treatment of cancer, fine chemical synthesis and treatment of wastewater. Emission spectra were measured in a FLS980 Fluorescence Spectrometer equipped with a 450 W Xe lamp, a 60 W microsecond flashlamp, and single monochromators.